Nonuniform wall pipe



June 24, 1969 E. c. BAUER, JR 3,451,434

NONUN IFORM WALL PIPE Filed Oct. 21, 1965 Jwarze/ k @erce C UnitedStates Patent 3,451,434 NONUNIFORM WALL PIPE Eugene C. Bauer, Jr., 729Cumberland Ave., Park Ridge, 1]]. 60068 Filed Oct. 21, 1965, Ser. No.499,600 Int. Cl. F16] 9/02, 57/00 US. Cl. 138-172 3 Claims ABSTRACT OFTHE DISCLOSURE This invention relates to pipe having superior servicecharacteristics and more particularly to ferrous pipe having anincreased thickness over a portion of the circumference so as toincrease its wear resistance.

The generating utility industry has long been faced with the problem ofremoving highly abrasive material or aggregate such 'as' slag, from coalburners to a refuse area. This slag is the residue or cinders of theunburned coal which is collected from the furnaces, in some instancesis, crushed, and is then transported in a water carrier through'pipesformed of numerous pipe sections tothe'refus'e' site. Since the slag isgenerally in discrete pieces ofa size and specific gravity whereby it isnot actually suspended"in' the water carrier, the slag is transportedthrough the pipe so that it is in fairly continuous contact with thebottom segment of the pipe circumference. The characteristics oftheslagparticles or pieces are such that the contact .with the lower pipe innerwall tends to wear or erode that portion of the pipe much more rapidly.than therernaining inner wall circumference. Consequently, this segmentof the pipe wall wears out long before the other wall segment is worn.

Heretofore, it has been the practice in the industry to estimate ormeasure the wear in concentric-walled pipe, i.e., a pipe having aconstant thickness wall around the entire circumference, and to rotatethe pipe during service so as to position the upper Wall segment at thebottom where the greatest wear occurs. It will be readily appreciatedthat where the pipe length is substantial, for example, several miles inlength, this service rotation requires appreciable labor with attendanthigh costs.

A similar problem exists in other pipe applications where a fluidcarrier transports an aggregate. For example, it has been founddesirable in some situations to pump concrete through pipe sectionswherein the cementitious matrix carries an aggregate of stone. Indredging operations, pipe sections may be used to transport sand andgravel with a water carrier. An air or other gas carrier may also beused in pumping sand through pipe sections within a foundry; or air maybe used to carry away the metal chips from machine tool operations.

Accordingly, it is an object of this invention to provide a pipe sectionhaving a wall construction wherein the outer wall shape is substantiallycircular in cross-section and the inner wall shape cross-section isnonuniform or nonsymmetrical so that the lower circumferential portionof the pipe wall is of substantially greater thickness than theremainder of the pipe wall.

It is another object of this invention to provide a pipe section havinga nonuniform wall thickness in which the thinnest wall circumferentialor arcuate segment is located 3,451,434 Patented June 24, 1969 ice nearthe top of the pipe section and which gradually and continuouslyincreases in thickness along the circumference to the bottomcircumferential or arcuate segment which has the greatest thickness.

It is still another object of the present invention to provide a pipesection of the above-described type wherein the thinnest wallcircumferential segment encompasses an approximately arc and the bottomcircumferential segment of greatest wall thickness also encompasses anapproximately 120 arc.

It is yet another object of the present invention to provide a pipesection of the above-described type wherein the wall thickness issubstantially symmetrical about a vertical center line.

For a better understanding of the invention together with other furtherobjects thereof, reference should now be made to the following detaileddescription which is to be read in conjunction with the accompanyingdrawing in which:

FIGURE 1 is a perspective view of a pipe section constructed inaccordance with the present invention;

FIGURE 2 is a side elevation view of the pipe section shown in FIGURE 1;

FIGURE 3 is a cross-sectional view of the pipe shown in FIGURE 1; and

FIGURE 4 is a side elevation view showing a transition pipe section forconnecting a concentric-walled pipe a wall cross-sectional thicknesswhich is nonuniform. Theouter wall shape 26 is substantially circular.The inner wall shape 28 is irregular or nonsymmetrical about ahorizontal transverse axis so that the wall 30 thickness varies from thethinnest circumferential wall segment 32 at the top of the pipe sectionto the thickest wall segment 34 at'the bottom of the pipe. Theintermediate segments 36 form a continuous wall surface which joins theseg-' ments 32, 34 to form a smooth inner pipe section wall free ofsharp changes which Would interfere with mixture.

flow. In this regard, it is to be noted that the segments 32 and 34 arenot constant in thickness but vary somewhat so as to provide acontinuous curve around the entire nonuniform periphery. The pipesection 20 is preferably formed symmetrically about the verticalcenter-line 38. It should also be noted that the pipe section ispreferably constructed of a ferrous or other substantially wearresistant material.

In FIGURE 4 a transition pipe section 40 is shown for connecting theabove described nonuniform thickness wall section 20 to aconcentrically-walled section. It Will be seen that the upper wallsegment 42 is substantially of uniform thickness while the lower wallsegment 44 longitudinally increases in thickness along the pipe section.

The pipe section 20 in FIGURES 1 through 3 is typical of the variationin wall thickness. The thinnest circumferential wall segment 32 isfairly constant in thickness over an arcuate portion of approximately120. In a pipe section having an outside diameter of 9% inches, forexample, this thickness will be approximately /2 inch. The symmetricalintermediate wall segments .36 each encompass an arc of approximately 60and in a pipe of the aforementioned size the wall thickness varies from/2 inch to nearly 2 inches. The bottom circumferential wall segment 34,having the greatest thickness, is nearly constant at a 2 inch thickness.

' It will be apparent to those skilled in the art that theabove-described Segments will not be limited to the arcs stated but mayvary depending upon several factors, though the lower wall segmentswill, of course, always be greater in thickness. The relative wallthicknesses will depend, for example, upon the size of the abrasivepieces which are intended to be transported through the pipe in thefluid carrier. The amount in volume or weight of these pieces relativeto the volume or weight of fluid will also be a determinant as well asthe velocity and quantity of mixture which is pumped through the pipe.These parameters are not intended to be exclusive or necessarily thoseof greatest significance in designing the pipe sections in accordancewith the present invention but are suggestive of the considerationswhich are involved in constructing a pipe section having the novel anddesirable characteristics now described.

The nonuniform wall pipe section, as previously indicated, is intendedfor use in transporting a mixture comprising an insoluble aggregate in afluid carrier. Since the fluid flow will not always carry the aggregatein the true suspended sense, these rough abrasive pieces will be sluicedalong the bottom segment of the pipe sections and in frequent contacttherewith. The abrasive nature of this aggregate will erode or wear thebottom segment of the pipe sections much more rapidly than that portionof the pipe wall which is contacted only by the fluid. Rather than allowa concentrically-walled pipe to erode irregularly, the variablethickness of the walls of the present invention will result in a wallwearing such that the lower segment will be worn-out at substantiallythe same time as the upper segment. Thus, no service rotation of thepipe will be required. The material and manufacturing costs of a pipeconstructed in accordance with the present invention, however, will becompetitive with standard uniform wall thickness pipe sections.

While a preferred embodiment of the present invention has been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects. Accordingly, it is the aim of the appended claimsto cover all such changes and modifications as wall within the truespirit and scope of the invention.

I claim:

1. A heavy-duty metal pipe section for transporting a mixture comprisingan abrasive aggregate and a fluid, said pipe section having a nonuniformthickness wall with the greatest thickness disposed in position toreceive the greatest wear from the mixture passing therethrough, saidwall having a substantially circular outer surface and an inner surfacewhich is nonsymmetrical about a transverse horizontal axis andsubstantially symmetrical about a transverse vertical axis, said wallcomprising an upper circumferential segment having the least thicknessof the wall, a lower circumferential segment having the greatestthickness of the wall, said upper and lower circumferential segmentsvarying slightly in thickness, and intermediate circumferential segmentsjoining said upper and lower segments, said intermediate segments havinga constantly increasing thickness from the juncture with said uppercircumferential segment to the juncture with said lower circumferentialsegment so that a continuous metal Wall is formed.

2. A pipe for transporting a mixture comprising an abrasive aggregateand a fluid in accordance with claim 1 wherein said uppercircumferential segment encompasses an arc of approximately and saidlower circumferential segment encompasses an arc of no more than 120.

3. A pipe for transporting a mixture comprising an abrasive aggregateand a fluid in accordance with claim 1 additionally including anelongated rib integrally mounted in the center of said uppercircumferential segment parallel with the longitudinal axis of said pipesection.

References Cited HOUSTON S. BELL, JR., Primary Examiner.

US. Cl. X.R.

